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Tank History - World War II

World War II did more than force armies to integrate all the available arms at every level into a mobile, flexible team. The mechanized combined arms force came of age in this war. In 1939, most armies still thought of an armored division as a mass of tanks with relatively limited support from the other arms. By 1943, the same armies had evolved armored divisions that were a balance of different arms and services, each of which had to be as mobile and almost as protected as the tanks they accompanied. This concentration of mechanized forces in a small nuaber of mobile divisions left the ordinary infantry unit deficient in both antitank weapons for the defense and armor to accompany the deliberate attack. The German, Soviet, and American armies therefore developed a number of tank surrogates such as tank destroyers and assault guns to perform these functions in cooperation with the infantry.

Armor experts in most armies, however, were determined to avoid being tied to the infantry, and in any event a tank was an extremely complicated, expensive, and therefore scarce weapon. The British persisted for much of the war on a dual track of development, remaining heavy tanks to support the infantry and lighter, more mobile tanks for independent armored formations. The Soviets similarly produced an entire series of heavy breakthrough tanks.

World War II began in September 1939 and gave the Army new insight into its tank needs. Of course, the Army concentrated on producing and improving the new standardized models. By 1940, the Army concentrated on designing and specifying the combat tanks needed in the near future. As a result, the Army did an unprecedented thing: a new tank was placed in production without ever assigning it a T experimental number. These machines were the M3 Mediums (Lee or Grant), mounting a 75mm gun in the right-hand corner of the hull and a 37mm gun in a top turret. This tank was designed in 1940, and it was the first World War II Allied tank mounting a 75mm gun. When the British employed it in combat in North Africa, it proved that the U.S. Army tank program had turned out to be outstanding.

Even as the M3 Medium was being rushed into production, the Army was working on the T6 Medium, using the lower hull, power train, suspension and tracks of the M3 but with a 75mm main gun in a full turret. The T6, when standardized and ordered into production in 1941, became the famous M4 Medium Sherman, and it is the only World War II tank still in service.

Another less successful development begun in 1940 was the T1 Heavy supertank, a 60-ton monster even by present standards, mounting a three-inch, high-velocity antiaircraft gun in its turret. It had a 1,000-horsepower engine and a speed of 25 mph. Although it was standardized as the M6 Heavy in 1941 and production was begun, this most powerful tank of its day was never used in combat because of problems in shipping it and using it on the roads and bridges of Europe.

In 1941, the Army also began production of its new M3 Light Tank, mounting a 37mm gun in its turret. It was a better-armored and -armed version of the M2 Light. One last non-convertible Christie was also built as the 57mm Gun Motor Carriage T49, but it was not successful. Based on designs begun in 1940, the 76mm Gun Motor Carriage T67 was built in 1942. This was the first U.S. Army armored vehicle using a turret-mounted gun and the torsion-bar suspension invented in 1933. It is sort of an interesting footnote that while the U.S. Armys volute suspension introduced in 1934 and so successful that it is still used takes up no interior hull space, it was replaced by the torsion-bar suspension, which uses a good hunk of interior hull space.

The first production vehicle using torsion bars was the 76mm Gun Motor Carriage M18 (Hellcat) introduced in 1943 and developed from the T67. The torsion-bar suspension was also used in the later M24 Light (Chaffee) and the M26 Heavy (later M26 Medium Pershing). U.S. Army tanks through the M60 were developed directly from the M26 Pershing.

During the war, German tank design went through at least three generations, plus constant minor variations. The first generation included such unbattleworthy prewar vehicles as the Mark, (or Panzerkampfwagen) I and II, which were similar to the Russian T-26 and T series and to the British cruiser tanks. The Germans converted their tank battalions to a majority of Mark III and IV medium tanks after the 1940 French campaign, thereby stealing a march on the Soviets and British, who still possessed obsolete equipment. However, the appearance of a few of the new generation T-34 and KV-1 tanks in Russia during 1941 compelled the Germans to begin a race for superior armor and gunpower. The third generation included many different variants, but the most important designs were the Mark V (Panther) and Mark VI (Tiger) tanks. Unfortunately for the Germans, their emphasis on proteotion and gunpower compromised the mobility and reliability of their tanks. In 1943, for example, Germany manufactured only 5,966 tanks, as compared to 29,497 for the US, 7,476 for Britain, and an estimated 20,000 for the Soviet Union.

The alternative to constant changes in tank design was to standardize a few basic designs and mass produce them even though technology had advanced to new improvements. This was the solution of Germany's principal opponents. The Soviet T-34, for example, was an excellent basic design that survived the war with only one major change in armament, (76.2-mm to 85-mm main gun).

The United States had even more reason to standardize and mass produce than did the Soviet Union. By concentrating on mechanical reliability, the US was able to produce vehicles that operated longer with fewer repair parts. To ensure that American tanks were compatible with American bridging equipment, the War Department restricted tank width to inches and maximum weight to thirty tons. The army relaxed these requirements only in late 1944.

The devastating firepower and speed of the U.S. Army's armored divisions of World War II was largely the result of the genius of American industry. When Germany invaded western Europe in 1940, the US Army had only 28 new tanks- 18 medium and 10 light- and these were soon to become obsolete, along with some 900 older models on hand. The Army had no heavy tanks and no immediate plans for any. Even more serious than the shortage of tanks was industry's lack of experience in tank manufacture and limited production facilities. Furthermore, the United States was committed to helping supply its allies. By 1942 American tank production had soared to just under 25,000, almost doubling the combined British and German output for that year. And in 1943, the peak tank production year, the total was 29,497. All in all, from 1940 through 1945, US tank production totaled 88,410.

Tank designs of World War II were based upon many complex considerations, but the principal factors were those thought to be best supported by combat experience. Among these, early combat proved that a bigger tank was not necessarily a better tank. The development goal came to be a tank combining all the proven characteristics in proper balance, to which weight and size were only incidentally related. Top priority went to mechanical reliability and firepower. Almost as important were maneuverability, speed, and good flotation (low ground pressure). Armor protection for the crew was perhaps less important, although it remained a highly desirable characteristic.

The problem here was that only a slight addition to the thickness of armor plate greatly increased the total weight of the tank, thereby requiring a more powerful and heavier engine. This, in turn, resulted in a larger and heavier transmission and suspension system. All of these pyramiding increases tended to make the tank less maneuverable, slower, and a larger and easier target. Thicker armor plate beyond a certain point, therefore, actually meant less protection for the crew. Determining the point at which the optimum thickness of armor was reached, in balance with other factors, presented a challenge that resulted in numerous proposed solutions and much disagreement.

According to Lt. Gen. Lesley J. McNair, Chief of Staff of GHQ, and later Commanding General, Army Ground Forces, the answer to bigger enemy tanks was more powerful guns instead of increased size. And, in his high positions, General McNair understandably exerted much influence upon the development of tanks, as well as antitank guns.

Since emphasis of the using arms was upon light tanks during 1940 and 1941, their production at first was almost two to one over the mediums. But in 1943, as the demand grew for more powerful tanks, the lights fell behind, and by 1945 the number of light tanks produced was less than half the number of mediums.

Armor, as the ground arm of mobility, emerged from World War II with a lion's share of the credit for the Allied victory. Indeed, armor enthusiasts at that time regarded the tank as being the main weapon of the land army. In 1945-46, the General Board of the US European Theater of Operations conducted an exhaustive review of past and future organization. The tank destroyer was deemed too specialized to justify in a peacetime force structure. In a reversal of previous doctrine, the US Army concluded that "the medium tank is the best antitank weapon." Although such a statement may have been true, it ignored the difficulties of designing a tank that could outshoot and defeat all other tanks.

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